Liquid crystal display device including data line divided into first and second branch lines and method of fabricating the same

ABSTRACT

An array substrate for a liquid crystal display device includes: a substrate; a gate line on the substrate; a data line crossing the gate line to define a pixel region including a transmissive portion and a reflective portion, the data line being divided into first and second branch lines, the first and second branch lines being spaced apart from each other and disposed in the reflective portion of the adjacent pixel regions, respectively; a thin film transistor connected to the gate line and the data line; a reflective electrode corresponding to the reflective portion and covering the first and second branch lines; and a transparent electrode corresponding to the transmissive portion and connected to the reflective electrode.

The present invention claims the benefit of Korean Patent ApplicationNo. 2003-29824, filed in Korea on May 12, 2003, which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device and a method offabricating a display device, and more particularly, to a liquid crystaldisplay device having a high aperture ratio and a high brightness, and amethod of fabricating the same.

2. Discussion of the Related Art

In general, a transflective liquid crystal display (LCD) device can beswitched from a transmissive mode using transmission of light to areflective mode using reflection of light according to the user'sselection. Since the transflective LCD device uses light from abacklight unit and ambient artificial or natural light, thetransflective LCD device is not restricted by environmental light andhas advantages, such as low power consumption and high brightness.

FIG. 1 is an exploded perspective view of a transflective liquid crystaldisplay device according to the related art. In FIG. 1, a transflectiveliquid crystal display (LCD) device 11 includes a first substrate 21 anda second substrate 15, and a liquid crystal layer 23 interposedtherebetween. The first substrate 21 and the second substrate 15 arespaced apart from each other and include a plurality of pixel regions“P” having a transmissive portion “A” and a reflective portion “C.” Ablack matrix 16 and a color filter layer 17 including red, green andblue sub-color filters are formed on the second substrate 15. A commonelectrode 13 is formed on the black matrix 16 and the color filter layer17.

A transparent pixel electrode 46 and a reflective electrode 40 areformed on the first substrate 21. The transparent pixel electrode 46 andthe reflective electrode 40 correspond to the transmissive portion “A”and the reflective portion “C,” respectively. A gate line 25 formed onthe first substrate 21 crosses a data line 27 to define the pixel region“P.” A thin film transistor (TFT) “T” of a switching element connectedto the gate line 25 and the data line 27 is disposed in matrix.

The black matrix 16 corresponding to the gate line 25, the data line 27and the TFT “T” is designed with an alignment margin. Alignment errorsbetween the first substrate 21 and the second substrate 15 can becompensated within the alignment margin. Accordingly, the black matrix16 is enlarged to accommodate the alignment margin.

FIG. 2 is a schematic cross-sectional view taken along a line “II—II ”of FIG. 1 and FIG. 3 is a magnified cross-sectional view of a portion“E” of FIG. 2. In FIGS. 2 and 3, a thin film transistor (TFT) “T”including a gate electrode 8, an active layer 30, an ohmic contact layer32, a source electrode 34 and a drain electrode 36 is formed on a firstsubstrate 21. A first pixel region “P1” and a second pixel region “P2”both contain a transmissive portion “A” and a reflective portion “C.” Atransparent pixel electrode 46 is formed to correspond to both thetransmissive portion “A” and the reflective portion “C.” A reflectiveelectrode 40 is formed in correspondence with the reflective portion“C.” A data line 27 is formed in a portion between the reflectiveportion “C” and the second pixel region “P2.” Although not shown inFIGS. 2 and 3, a gate line crosses the data line 27.

A color filter layer 17, including a red sub-color filter 17 a, greensub-color filters 17 b and a blue sub-color filter 17 c, is formed inthe pixel regions “P1” and “P2” on a second substrate 15 facing thefirst substrate 21. A black matrix 16 is formed to correspond to thedata line 27. When a space between the adjacent reflective electrodes 40over the data line 27 has a first distance “a” and a portion of thereflective electrodes 40 overlapping the data line 17 have a seconddistance “b,” the black matrix 16 has a width “a+2b.”

A uniform electric field is not sufficiently applied to a liquid crystallayer corresponding to the space between the adjacent reflectiveelectrodes 40. Accordingly, the liquid crystal layer 23 (of FIG. 2)corresponding to the space between the adjacent reflective electrodes 40has a light leakage even when a voltage corresponding to a black imageis applied to the transparent pixel electrode 46 (of FIG. 2) in anormally white mode LCD device. Thus, the liquid crystal layer 23 (ofFIG. 2) corresponding to the space between the adjacent reflectiveelectrodes 40 would be shielded by the black matrix 16. Moreover, sincethe first substrate 21 and second substrate 15 can have an alignmenterror therebetween, the black matrix is designed to have the portionhaving the second distance “b” corresponding to the alignment margin.Accordingly, the black matrix 16 is enlarged and an effective area ofthe reflective portion “C” is reduced, thereby degrading aperture ratioand brightness.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a liquid crystaldisplay device and a method of fabricating a liquid crystal displaydevice that substantially obviates one or more of the problems due tolimitations and disadvantages of the related art.

An object of the present invention is to provide a liquid crystaldisplay device having improved aperture ratio and brightness.

Another object of the present invention is to provide a method offabricating a liquid crystal display device having improved apertureratio and brightness.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, an arraysubstrate for a liquid crystal display device includes: a substrate; agate line on the substrate; a data line crossing the gate line to definea pixel region including a transmissive portion and a reflectiveportion, the data line being divided into first and second branch lines,the first and second branch lines being spaced apart from each other anddisposed in the reflective portion of the adjacent pixel regions,respectively; a thin film transistor connected to the gate line and thedata line; a reflective electrode corresponding to the reflectiveportion and covering the first and second branch lines; and atransparent electrode corresponding to the transmissive portion andconnected to the reflective electrode.

In another aspect, a fabricating method of an array substrate for aliquid crystal display device includes: forming a gate line on asubstrate; forming a data line crossing the gate line to define a pixelregion including a transmissive portion and a reflective portion, thedata line being divided into first and second branch lines, the firstand second branch lines being spaced apart from each other and disposedin the reflective portion of the adjacent pixel regions, respectively;forming a thin film transistor connected to the gate line and the dataline; forming a reflective electrode corresponding to the reflectiveportion and covering the first and second branch lines; and forming atransparent electrode corresponding to the transmissive portion andconnected to the reflective electrode.

In another aspect, a liquid crystal display device includes: first andsecond substrates spaced apart from each other; a gate line on the firstsubstrate; a data line crossing the gate line to define a pixel regionincluding a transmissive portion and a reflective portion, the data linebeing divided into first and second branch lines, the first and secondbranch lines being spaced apart from each other and disposed in thereflective portion of the adjacent pixel regions, respectively; a thinfilm transistor connected to the gate line and the data line; areflective electrode corresponding to the reflective portion andcovering the first and second branch lines; a transparent electrodecorresponding to the transmissive portion and connected to thereflective electrode; a color filter layer on the second substrate; acommon electrode on the color filter layer; and a liquid crystal layerbetween the reflective electrode and the common electrode.

In another aspect, a liquid crystal display device includes: first andsecond substrates spaced apart from each other; a gate line on the firstsubstrate; a data line crossing the gate line to define a pixel regionincluding a transmissive portion and a reflective portion, the data linebeing divided into first and second branch lines, the first and secondbranch lines being spaced apart from each other and disposed in thereflective portion of the adjacent pixel regions, respectively; a thinfilm transistor connected to the gate line and the data line; areflective electrode corresponding to the reflective portion andcovering the first and second branch lines; a transparent electrodecorresponding to the transmissive portion and connected to thereflective electrode; a color filter layer on the reflective electrode;a common electrode on the second substrate; and a liquid crystal layerbetween the color filter layer and the common electrode.

In another aspect, a fabricating method of a liquid crystal displaydevice includes: forming a gate line on a first substrate; forming adata line crossing the gate line to define a pixel region including atransmissive portion and a reflective portion, the data line beingdivided into first and second branch lines, the first and second branchlines being spaced apart from each other and disposed in the reflectiveportion of the adjacent pixel regions, respectively; forming a thin filmtransistor connected to the gate line and the data line; forming areflective electrode corresponding to the reflective portion andcovering the first and second branch lines; forming a transparentelectrode corresponding to the transmissive portion and connected to thereflective electrode; forming a color filter layer on a secondsubstrate; forming a common electrode on the color filter layer;attaching the first and second substrates such that the reflectiveelectrode faces the common electrode; and forming a liquid crystal layerbetween the reflective electrode and the color filter layer.

In another aspect, a fabricating method of a liquid crystal displaydevice includes: forming a gate line on a first substrate; forming adata line crossing the gate line to define a pixel region including atransmissive portion and a reflective portion, the data line beingdivided into first and second branch lines, the first and second branchlines being spaced apart from each other and disposed in the reflectiveportion of the adjacent pixel regions, respectively; forming a thin filmtransistor connected to the gate line and the data line; forming areflective electrode corresponding to the reflective portion andcovering the first and second branch lines; forming a transparentelectrode corresponding to the transmissive portion and connected to thereflective electrode; forming a color filter layer on the reflectiveelectrode; forming a common electrode on a second substrate; attachingthe first and second substrates such that the color filter layer facesthe common electrode; and forming a liquid crystal layer between thecolor filter layer and the common electrode.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is an exploded perspective view of a transflective liquid crystaldisplay device according to the related art.

FIG. 2 is a schematic cross-sectional view taken along a line “II—II” ofFIG. 1.

FIG. 3 is a magnified cross-sectional view of a portion “E” of FIG. 2.

FIG. 4 is a cross sectional view of a liquid crystal display deviceaccording to a first embodiment of the present invention.

FIG. 5 is a plane view of an array substrate of a liquid crystal displaydevice according to a first embodiment of the present invention.

FIGS. 6A to 6D are cross-sectional views, which are taken along a line“VI—VI” of FIG. 5, showing a fabricating process of an array substratefor a liquid crystal display device according to a first embodiment ofthe present invention.

FIG. 7 is a cross-sectional view of a liquid crystal display deviceaccording to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a liquid crystal display deviceaccording to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRAED EMBODIMENTS

Reference will now be made in detail to the illustrated embodiments ofthe present invention, an example of which is illustrated in theaccompanying drawings.

FIG. 4 is a cross sectional view of a liquid crystal display deviceaccording to a first embodiment of the present invention. As shown inFIG. 4, a first substrate 100 and a second substrate 200 can be disposedto face and be spaced apart from each other. A thin film transistor(TFT) “T” having a gate electrode 102, an active layer 110, a sourceelectrode 114 and a drain electrode 116 are formed on an inner surfaceof the first substrate 100. In addition, a data line 118, including afirst branch line 118 a and a second branch line 118 b, and a gate line(not shown) are formed on an inner surface of the first substrate 100.The data line 118 is connected to the source electrode 114, and isdivided into first branch line 118 a and a second branch line 118 b atan end portion of the first substrate 100. The first branch line 118 aand the second branch line 118 b are spaced apart from each other todefine a space “D.” A width of the first branch line 118 a can be thesame as a width of the second branch line 118 b. The gate line isconnected to the gate electrode 102. The gate line and the data line 118cross each other to define a first pixel region “P1” and a second pixelregion “P2.”

A first passivation layer 120 is formed on an entire surface of thefirst substrate 100 having the TFT “T” and the data line 118. Atransparent electrode 122 is formed on the first passivation layer 120to correspond to the space “D” between the first branch line 118 a andthe second branch line 118 b. A second passivation layer 124 is formedon the transparent electrode 122.

A reflective electrode 132 connected to the drain electrode 116 and thetransparent electrode 122 is formed on the second passivation layer 124.The reflective electrode 122 can include an unevenness to increasebrightness along a slant angle and to prevent mirror reflection. Theunevenness can be indirectly obtained by forming the second passivationlayer 124 to have an uneven portion “F” at a surface thereof.

The reflective electrode 132 includes a first reflective electrode 132 ain the first pixel region “P1” and a second reflective electrode 132 bin the second pixel region “P2” adjacent to the first pixel region “P1.”The first branch line 118 a and the second branch line 118 b are formedunder the first reflective electrode 132 a and the second reflectiveelectrode 132 b, respectively. Since the transparent electrode 122connected to the drain electrode 116 is formed in the space “D” betweenthe first branch line 118 a and the second branch line 118 b, light froma backlight unit (not shown) under the first substrate 100 passesthrough the space “D” and is emitted to exterior. Accordingly, the space“D” and the reflective electrode 132 corresponds to a transmissiveportion “A” and a reflective portion “C,” respectively. Each pixelregion “P1” and “P2” includes the transmissive portion “A” and thereflective portion “C.” The second passivation layer 124 can be formedto have a groove 130 corresponding to the transmissive portion “A” for adual cell gap.

A color filter layer 202, including a red sub-color filter 202 a, agreen sub-color filter 202 b and a blue sub-color filter 202 c, isformed on an inner surface of the second substrate 200, and atransparent common electrode 204 is formed on the color filter layer202. A liquid crystal layer 190 is formed between the reflectiveelectrode 132 and the common electrode 204. When the second passivationlayer 124 has the groove 130 corresponding to the transmissive portion“A,” the liquid crystal layer 190 can have a first thickness “2d” in thetransmissive portion “A” and a second thickness “d” in the reflectiveportion “C,” wherein the first thickness “2d” is substantially twice asgreat as the second thickness “d.”

In the first embodiment, since the data line 118 is formed under thereflective electrode 132 in the reflective portion “C” of the firstregion “P1” and the second pixel region “P2,” a black matrixcorresponding to the data line 118 can not be formed on the secondsubstrate 200. Moreover, since the transparent electrode 122 is formedin the space “D” between the first branch line 118 a and the secondbranch line 118 b, a black matrix corresponding to the space “D” may notbe necessary. In addition, since the space “D” between the first branchline 118 a and the second branch line 118 b is used as the transmissiveportion “A,” aperture ratio is further improved.

FIG. 5 is a plane view of an array substrate of a liquid crystal displaydevice according to a first embodiment of the present invention. Asshown in FIG. 5, a gate line 106 and a data line 118 cross each other todefine a first region “P1” and a second pixel region “P2” that bothrespectively include a transmissive portion “A” and a reflective portion“C.” The data line 118 is divided into a first branch line 118 a and asecond branch line 118 b at an end of a substrate 100. A thin filmtransistor (TFT) “T,” including a gate electrode 102, an active layer110, a source electrode 114 and a drain electrode 114, is formed nearthe crossing of the gate line 106 and the data line 118. The gateelectrode 102 is connected to the gate line 106 and the source electrode114 is connected to the data line 118. The source electrode 114 and thedrain electrode 116 are spaced apart from each other.

A transparent electrode 122 is formed to correspond to the transmissiveportion “A” of the first regions “P1” and the second pixel region “P2.”A reflective electrode 132 having an unevenness (not shown) is formed tocorrespond to the reflective portion “C.” The reflective electrode 132is connected to the drain electrode 116 through a drain contact hole126. Further, the reflective electrode 132 is connected to thetransparent electrode 122 through a transparent electrode contact hole128. The first branch line 118 a and second branch line 118 b are formedunder the reflective electrodes in the first pixel region “P1” and thesecond pixel region “P2,” respectively. Widths of the first branch line118 a and second branch line 118 b can be determined such that a sum ofthe widths of the first branch line 118 a and second branch line 118 bis substantially the same as a width of the data line 27 discussed abovein reference to FIG. 2 for an LCD device of the related art so as not toaffect the resistance of the data line 118. In addition, a width of thefirst branch line 118 a is substantially the same as a width of thesecond branch line 118 b. Moreover, the first branch line 118 a andsecond branch line 118 b can have at least one connection pattern (notshown) connecting the first branch line 118 a and second branch line 118b of one data line 118. Such a connection pattern can overlap the gateline 106.

In the first embodiment, since the data line 118 is formed under thereflective electrode 132 in the reflective portion “C” of both the firstand second pixel regions “P1” and “P2,” a black matrix corresponding tothe data line 118 can be omitted. Moreover, since the transparentelectrode 122 is formed in a space “D” between the first branch line 118a and second branch line 118 b, a black matrix corresponding to thespace “D” can also be omitted. In addition, since the space “D” betweenthe first branch line 118 a and second branch line 118 b is used as thetransmissive portion “A,” aperture ratio and brightness are furtherimproved.

FIGS. 6A to 6D are cross-sectional views, which are taken along a line“VI—VI” of FIG. 5, showing a fabricating process of an array substratefor a liquid crystal display device according to a first embodiment ofthe present invention. As shown in FIG. 6A, a gate line 106, asdescribed in reference to FIG. 5, and a gate electrode 102 are formed ona substrate 100. Since resistance of the gate line 106 causes an RC(resistance-capacitance) delay, a material having low resistance can beused for the gate line 106. For example, aluminum (Al) can be used forthe gate line 106 to reduce RC delay. Pure aluminum (Al), however, haslow chemical resistance and may cause line defects, such as a hillock,in a subsequent high temperature process. Accordingly, aluminum (Al)alloy, such as aluminum neodymium (AlNd), and a multiple layer includingan aluminum layer, such as aluminum/molybdenum (Al/Mo), can be used forthe gate line 106.

A gate insulating layer 108 is formed on an entire surface of thesubstrate 100 including the gate line 106 and the gate electrode 102.The gate insulating layer can include an inorganic material, such assilicon nitride (SiN_(x)) and silicon oxide (SiO₂). An active layer 110of amorphous silicon (a-Si:H) and an ohmic contact layer 112 ofimpurity-doped amorphous silicon (n+a-Si:H) are sequentially formed onthe gate insulating layer 108. The active layer 110 and the ohmiccontact layer 112 have an island shape.

As shown in FIG. 6B, a source electrode 114 and a drain electrode 116are formed on the ohmic contact layer 112 by depositing and patterningone of a conductive metal group including chromium (Cr), molybdenum(Mo), antimony (Sb) and titanium (Ti). At the same time, a data line 118can be formed on the gate insulating layer 108. The data line 118 isconnected to the source electrode 114 and crosses the gate line 106 todefine a first pixel region “P1” and a second pixel region “P2” thatboth include a transmissive portion “A” and a reflective portion “C.”The data line 118 is divided into a first branch line 118 a and a secondbranch line 118 b at one end of the substrate 100. The first branch line118 a and second branch line 118 b are disposed in the reflectiveportions “C” of the adjacent first pixel region “P1” and the secondpixel region “P2,” respectively. The first branch line 118 a and secondbranch line 118 b can have at least one connection pattern (not shown)connecting the first branch line 118 a and second branch line 118 b ofone data line 118. Such a connection pattern can overlap the gate line106.

A first passivation layer 120 of an organic insulating material, such asbenzocyclobutene (BCB) and acrylic resin, is formed on an entire surfaceof the substrate 100 including the source electrode 114, the drainelectrode 116 and the data line 118. A transparent electrode 122 isformed on the first passivation layer 120 by depositing and patterning atransparent conductive material, such as indium-tin-oxide (ITO) andindium-zinc-oxide (IZO). The transparent electrode 122 can be formed tocorrespond to the transmissive portion “A,” which is defined by a spacebetween the first branch line 118 a and second branch line 118 b. Thetransparent electrode 122 extends such that one side of the transparentelectrode 122 is formed in the reflective portion “C.”

As shown in FIG. 6C, a second passivation layer 124 of an organicinsulating material, such as benzocyclobutene (BCB) and acrylic resin,is formed on an entire surface of the substrate 100, including thetransparent electrode 122. The second passivation layer 124 has anuneven portion “F” on its surface corresponding to the reflectiveportion “C.” The uneven portion “F” can be obtained through severalprocesses. For example, a first uneven pattern having a rectangularshape in a cross-sectional view can be formed by depositing andpatterning a photosensitive resin. The first uneven pattern can be curedto become a second uneven pattern having a semi-spherical shape in across-sectional view.

A drain contact hole 126 exposing the drain electrode 116, a transparentelectrode contact hole 128 exposing the transparent electrode 122 in thereflective portion “C” and a groove 130 exposing the transparentelectrode 122 in the transmissive portion “A” are formed by patterningthe first passivation layer 120 and the second passivation layer 124.The groove 130 corresponding to the transmissive portion “A” is formedto obtain a dual cell gap, where a first thickness “2d,” as discussedabove in reference to FIG. 4, (i.e., a first cell gap) in thetransmissive portion “A” is substantially twice as great as a secondcell gap “d,” as also discussed above in reference to FIG. 4, (i.e., asecond cell gap) in the reflective portion “C.” In a structure having adual cell gap, since the polarization property of the transmissiveportion becomes similar to that of the reflective portion, colordifference between the transmissive portion and the reflective portionis reduced.

As shown in FIG. 6D, a reflective electrode 132 is formed on the secondpassivation layer in the reflective portion “C” 124 by depositing andpatterning a reflective conductive metal, such as aluminum (Al) andsilver (Ag). The reflective electrode 132 is connected to both the drainelectrode 114 and the transparent electrode 122. Since the reflectiveelectrode 132 has an unevenness corresponding to the unevenness “F” ofthe second passivation layer 124, high reflectance is obtained andmirror reflection is prevented. A ratio of the transmissive portion “A”to the reflective portion “C” can be changed by adjusting a spacebetween the first branch line 118 a and the second branch line 118 b.

FIG. 7 is a schematic cross-sectional view of a liquid crystal displaydevice according to a second embodiment of the present invention. Asshown in FIG. 7, a first substrate 300 and a second substrate 400 arespaced apart from each other. A thin film transistor (TFT) “T” includinga gate electrode 302, an active layer 310, a source electrode 314 and adrain electrode 316 is formed on an inner surface of the first substrate300. A gate line (not shown) connected to the gate electrode 302 crossesa data line 318 connected to the source electrode 314 to define a firstpixel region “P1” and a second pixel region “P2.” The data line 318 isdivided into a first branch line 318 a and a second branch line 318 b atone end of the first substrate 300. A width of the first branch line 318a can be the same as a width of the second branch line 318 b.

A first passivation layer 320 is formed on an entire surface of thefirst substrate 300 including the TFT “T” and the data line 318. Atransparent electrode 322 is formed on the first passivation layer 320corresponding to a space “D” between the first branch line 318 a andsecond branch line 318 b. A second passivation layer 324 is formed onthe transparent electrode 322 and a reflective electrode 332 connectedto the drain electrode 316 and the transparent electrode 322 is formedon the second passivation layer 324. The reflective electrode 332 canhave an unevenness to increase brightness along a slant angle and toprevent mirror reflection. The unevenness can be indirectly obtained byforming the second passivation layer 324 to have an uneven portion “F”at a surface thereof.

The first branch line 318 a and second branch line 318 b are formedunder the reflective electrodes 332 of the first pixel region “P1” andthe second pixel region “P2,” respectively. Since the transparentelectrode 322 connected to the drain electrode 316 is formed in thespace “D” between the first branch line 318 a and second branch line 318b, light from a backlight unit (not shown) under the first substrate 300passes through the space “D” and is emitted to the exterior.Accordingly, the space “D” and the reflective electrode 332 correspondsto a transmissive portion “A” and a reflective portion “C,”respectively. Each pixel region “P1” and “P2” includes the transmissiveportion “A” and the reflective portion “C.”

A color filter layer 336, including red sub-color filter 336 a, greensub-color filter 336 b and blue sub-color filter 336 c, is formed on thereflective electrode 332 and the second passivation layer 324corresponding to the transmissive portion “A.” One of the red sub-colorfilter 336 a, green sub-color filter 336 b and blue sub-color filter 336c corresponds to one of the pixel regions “P1” and “P2.” Since the colorfilter layer 336 is formed on the first substrate 300, an alignmentmargin for attachment errors is not necessary. Accordingly, apertureratio is further improved. A transparent common electrode 402 is formedon an inner surface of the second substrate 400. A liquid crystal layer390 is formed between the color filter layer 336 and the commonelectrode 402.

FIG. 8 is a cross-sectional view of a liquid crystal display deviceaccording to a third embodiment of the present invention. To obtain anequal color property in the transmissive portion and the reflectiveportion, a liquid crystal display device including a color filter layerof a dual thickness can be used. As shown in FIG. 8, a first substrate300 and a second substrates 400 are spaced apart from each other. A thinfilm transistor (TFT) “T,” including a gate electrode 302, an activelayer 310, a source electrode 314 and a drain electrode 316, is formedon an inner surface of the first substrate 300. A gate line (not shown)connected to the gate electrode 302 crosses a data line 318 connected tothe source electrode 314 to define a first pixel region “P1” and asecond pixel region “P2.” The data line 318 is divided into a firstbranch line 318 a and a second branch line 318 b at one end of the firstsubstrate 300. A width of the first branch line 318 a can be the same asa width of the second branch line 318 b.

A first passivation layer 320 is formed on an entire surface of thefirst substrate 300 including the TFT “T” and the data line 318, and atransparent electrode 322 is formed on the first passivation layer 320corresponding to a space “D” between the first and second branch lines318 a and 318 b. A second passivation layer 324 is formed on thetransparent electrode 322 and a reflective electrode 332 connected tothe drain electrode 316 and the transparent electrode 322 is formed onthe second passivation layer 324. The reflective electrode 332 can havean unevenness to increase brightness along a slant angle and to preventmirror reflection. The unevenness can be indirectly obtained by formingthe second passivation layer 324 to have an uneven portion “F” at asurface thereof.

The first branch line 318 a and the second branch line 318 b are formedunder the reflective electrodes 332 of the first pixel region “P1” andthe second pixel region “P2,” respectively. Since the transparentelectrode 322 connected to the drain electrode 316 is formed in thespace “D” between the first branch line 318 a and the second branch line318 b, light from a backlight unit (not shown) under the first substrate300 passes through the space “D” and is emitted to exterior.Accordingly, the space “D” and the reflective electrode 332 correspondsto a transmissive portion “A” and a reflective portion “C,”respectively. Each pixel region “P1” and “P2” includes the transmissiveportion “A” and the reflective portion “C.”

The second passivation layer 324 has a groove 326 corresponding to thetransmissive portion “A.” A color filter layer 336, including redsub-color filter 336 a, green sub-color filter 336 b and blue sub-colorfilter, is formed on the reflective electrode 332 and the secondpassivation layer 324 corresponding to the transmissive portion “A.” Oneof the red sub-color filter 336 a, green sub-color filter 336 b and bluesub-color filter 336 c corresponds to one of the pixel regions “P1” and“P2.” The color filter layer 336 fills the groove 326 of the secondpassivation layer 324, thereby a first thickness “2t” of the colorfilter layer 336 in the transmissive portion “A” is substantially twiceas great as a second thickness “t” of the color filter layer 336 in thereflective portion “C.” Therefore, a uniform color purity property canbe obtained in the transmissive portion “A” and the reflective portion“C,” and an LCD device having a high display quality is obtained. Atransparent common electrode 402 is formed on an inner surface of thesecond substrate 400. A liquid crystal layer 390 is formed between thecolor filter layer 336 and the common electrode 402.

In an LCD device according to the second and third embodiments of thepresent invention, since the data line 318 is formed under thereflective electrodes 332 in the reflective portion “C” of the first andsecond pixel regions “P1” and “P2,” a black matrix corresponding to thedata line 318 can be omitted. Moreover, since the transparent electrode322 connected to the drain electrode 316 is formed in a space “D”between the first branch line 318 a and the second branch line 318 b, ablack matrix corresponding to the space “D” can also be omitted. Inaddition, since the space between the first branch line 318 a and thesecond branch line 318 b is used as the transmissive portion “A,”aperture ratio and brightness are further improved. Moreover, since thecolor filter layer 336 is formed on the first substrate 300, analignment margin for accommodating attachment errors is not necessaryand aperture ratio is further improved. In an LCD device according tothe third embodiment of the present invention, since the color filterlayer has a dual thickness such that a first thickness in thetransmissive portion “A” is substantially twice as great as a secondthickness in the reflective portion “C,” a uniform color purity propertyresulting in an LCD device having a high display quality can be obtainedin the transmissive portion “A” and the reflective portion “C.”

In an LCD device according to the present invention, a data line isdivided into first and second branch lines, and the first and secondbranch lines are disposed in reflective portions of adjacent pixelregions. As a result, a black matrix corresponding to the data line canbe omitted by utilizing a space between the first and second branchlines as a transmissive portion. Accordingly, aperture ratio andbrightness are improved. Moreover, when the LCD device includes a groovein the transmissive portion, a liquid crystal layer can have a firstthickness (i.e., a first cell gap) in the transmissive portion and asecond thickness (i.e., a second cell gap) in the reflective portionsuch that the first thickness is substantially twice as great as thesecond thickness. In an LCD device having a dual cell gap structure,since a uniform optical property is obtained in the transmissive portionand the reflective portion, a high display quality is obtained. Inaddition, since a color filter layer is formed on an array substrate,alignment margin for accommodating attachment errors is not necessaryand aperture ratio is further improved. Furthermore, an LCD devicehaving uniform color property in the transmissive portion and thereflective portion and high display quality can be obtained by forming acolor filter layer such that a first thickness of the color filter layerin the transmissive portion is substantially twice as great as a secondthickness of the color filter layer in the reflective portion.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the liquid crystal displaydevice and method of fabricating the same of the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An array substrate for a liquid crystal display device, comprising: asubstrate; a gate line on the substrate; a data line crossing the gateline to define a pixel region including a transmissive portion and areflective portion, the data line being divided into first and secondbranch lines, the first and second branch lines being spaced apart fromeach other and disposed in the reflective portion of the adjacent pixelregions, respectively; a thin film transistor connected to the gate lineand the data line; a reflective electrode corresponding to thereflective portion and covering the first and second branch lines; and atransparent electrode corresponding to the transmissive portion andconnected to the reflective electrode.
 2. The substrate according toclaim 1, wherein a width of the first branch line is substantially thesame as a width of the second branch line.
 3. The substrate according toclaim 1, wherein the thin film transistor includes a gate electrodeconnected to the gate line, an active layer, a source electrodeconnected to the data line, a drain electrode connected to thereflective electrode.
 4. The substrate according to claim 3, wherein theactive layer includes amorphous silicon (a-Si:H).
 5. The substrateaccording to claim 1, wherein the reflective electrode has at least oneof silver (Ag), aluminum (Al) and aluminum (Al) alloy.
 6. The substrateaccording to claim 1, wherein a surface of the reflective electrode hasan unevenness.
 7. The substrate according to claim 1, wherein thetransparent electrode has one of indium-tin-oxide (ITO) andindium-zinc-oxide (IZO).
 8. The substrate according to claim 1, whereina space between the first and second branch lines corresponds to thetransmissive portion.
 9. The substrate according to claim 1, furthercomprising a passivation layer between the transparent electrode and thereflective electrode.
 10. The substrate according to claim 9, whereinthe passivation layer includes a groove corresponding to thetransmissive portion.
 11. The substrate according to claim 1, furthercomprising a color filter layer on the reflective electrode.
 12. Thesubstrate according to claim 11, wherein one of red, green and bluesub-color filters in the color filter layer corresponds to the pixelregion.
 13. The substrate according to claim 11, wherein the colorfilter layer has a first thickness in the transmissive portion and asecond thickness in the reflective portion, the first thickness beingsubstantially twice as great as the second thickness.
 14. The substrateaccording to claim 11, further comprising a passivation layer betweenthe transparent electrode and the reflective electrode.
 15. Thesubstrate according to claim 14, wherein the passivation layer includesa groove corresponding to the transmissive portion.
 16. A fabricatingmethod of an array substrate for a liquid crystal display device,comprising: forming a gate line on a substrate; forming a data linecrossing the gate line to define a pixel region including a transmissiveportion and a reflective portion, the data line being divided into firstand second branch lines, the first and second branch lines being spacedapart from each other and disposed in the reflective portion of theadjacent pixel regions, respectively; forming a thin film transistorconnected to the gate line and the data line; forming a reflectiveelectrode corresponding to the reflective portion and covering the firstand second branch lines; and forming a transparent electrodecorresponding to the transmissive portion and connected to thereflective electrode.
 17. The method according to claim 16, wherein awidth of the first branch line is substantially the same as a width ofthe second branch line.
 18. The method according to claim 16, whereinthe thin film transistor includes a gate electrode connected to the gateline, an active layer, a source electrode connected to the data line, adrain electrode connected to the reflective electrode.
 19. The methodaccording to claim 16, wherein the reflective electrode has at least oneof silver (Ag), aluminum (Al) and aluminum (Al) alloy.
 20. The methodaccording to claim 16, wherein a surface of the reflective electrode hasan unevenness.
 21. The method according to claim 16, wherein thetransparent electrode has one of indium-tin-oxide (ITO) andindium-zinc-oxide (IZO).
 22. The method according to claim 16, wherein aspace between the first and second branch lines corresponds to thetransmissive portion.
 23. The method according to claim 16, furthercomprising forming a passivation layer between the transparent electrodeand the reflective electrode.
 24. The method according to claim 23,wherein the passivation layer includes a groove corresponding to thetransmissive portion.
 25. The method according to claim 16, furthercomprising forming a color filter layer on the reflective electrode. 26.The method according to claim 25, wherein one of red, green and bluesub-color filters in the color filter layer corresponds to the pixelregion.
 27. The method according to claim 25, wherein the color filterlayer has a first thickness in the transmissive portion and a secondthickness in the reflective portion, the first thickness beingsubstantially twice as great as the second thickness.
 28. The methodaccording to claim 25, further comprising forming a passivation layerbetween the transparent electrode and the reflective electrode.
 29. Themethod according to claim 28, wherein the passivation layer includes agroove corresponding to the transmissive portion.